Hollow barrier



FIG. 1 is a perspective view showing the top, rear, and one side of a hollow barrier illustrating my new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a side elevation view thereof showing the side which is visible in FIG. 1; and,

FIG. 7 is a side elevation view thereof showing the side opposite the side visible in FIG. 4. 

The ornamental design for hollow barrier, as shown and described. 